Résumé :
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The incidence of patients with neuromuscular diseases and a suspected mitochondrial diseases is very high. Most patients present with characteristics that are suggestive of a mitochondrial DNA (mtDNA) alteration including mosaic pattern of muscle histological alterations (cytochrome c oxidase deficient muscle fibres or ragged-red fibres), combined defect of the oxidative phosphorylation pathway, or a pattern of inheritance compatible with maternal transmission. In addition mtDNA alterations have to be excluded in patients without suggestive anomalies, for example in very young patients who are known to lack typical muscle histological alterations, or in the presence of an isolated complex I defect, which does not induce these histological alterations even when the underlying genetic alteration resides in one of the 7 mtDNA complex I structural subunit genes. As a consequence, analysis of the mtDNA sequence is a recurrent demand in centres specialized in neuromuscular disorders. Several techniques have been progressively developed to answer that demand including screening methods such as denaturing gradient gel electrophoresis, denaturing high performance liquid chromatography, the Surveyor technology based on the clivage of mispaired bases. We here report the results of a trial of a re-sequencing chip for mtDNA in 35 patients from La Pitié-Salpêtrière. This project has been conducted within the frame of a national trial of the French Mitochondrial Diseases network, using Affymetrix Gene Chip mitochondrial Resequencing 2.0 Array. Financial support from the GIS-MR provided the service of PartnerChip company for DNA handling (amplification, purification, digestion, hybridization) and data generation. Advantages and pitfalls of that approach are discussed.
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